Wireless communication devices are widely used, and have become an essential aspect of modern life. Wireless communication devices such as pagers, mobile phones, text pagers, PDA's (personal data assistants) are used for work, for personal activities, and as a way to keep in contact with family and friends. These wireless device are increasingly available in cars, boats, appliances, and entertainment equipment. As the number and type of these wireless devices increase, application developers continue to provide exciting and innovative applications to make the wireless devices easier to use, and to enhance their usefulness. Further, wireless service providers have invested heavily in infrastructure equipment to support higher data rates to wireless devices, and thereby are enabling a wide range of new and exciting applications.
More often, these wireless communication devices are provided with position location capability. To enable position location capability, the wireless device typically has a GPS receiver for receiving GPS satellite data. The wireless device may have a local processor for determining its position, or may rely on infrastructure equipment to assist in determining location. The growth in position location enabled devices is due in part to the implementation of the E911 system in the United States. The E911 system is mandated by the US Federal Communications Commission. Generally, the E911 system requires that the operator of a public wireless communication system, upon the request from an emergency center, report the location of the mobile device that has placed an emergency 911 call. Since location information processes and infrastructures have been added to support E911, other applications are evolving to utilize the position information. For example, mapping, traffic, weather, and shopping applications may benefit from information about a user's specific location.
These wireless handsets most often access a wireless network according to well defined and well established standards. For example, wireless handsets may operate according to the well-defined standards for CDMA, WCDMA, UMTS, CDMA2000, GSM, GPRS, EDGE, PHS, UTRAN, FOMA, AMPS, or other standard. More particularly, these standards have matured to allow for seamless movement within a network, as well as between networks, even when the service providers change. The telephony functions operating between the handset and the network are consistently applied and used according to well defined processes. In this way, basic voice communication and basic data transmission may be reliably, robustly, and seamlessly provided to the users of wireless handsets.
Wireless communications systems generally have base stations and antennas which communicate with mobile wireless devices. These wireless devices may accommodate voice communication as well as data communication. For example, the wireless devices may be mobile phones, personal data assistants, or laptop computers. Since they are portable, the wireless devices are usually powered by a battery, and need to be sized for convenient use. Most commercial wireless communication systems comply with some international or regional standard to assure compatibility between the base station and the mobile devices. However, since there are several communication standards, mobile devices can only communicate in a compatible communication system. Since this has been found to be too limiting, mobile wireless devices are often adapted to operate in more than one communication system.
Wireless communication systems are generally arranged to operate in particular frequency range or communication band. For example, one communication system may operate in the PCS band, which operates in frequency band at approximately 1900 MHz. Another communication system may operate in the cellular band, which operates in frequency band at approximately 800 MHz. It has been found to be desirable to have mobile wireless devices capable of operating at multiple communication bands, and thereby able to operate on multiple communication systems. For example, it has been found particularly useful to have wireless mobile devices capable of operating on both the PCS and cellular systems. It will be appreciated that other frequency bands and communications standards may be used.
It has also been found desirable that a mobile wireless device be constructed to receive an auxiliary signal. A particularly useful auxiliary signal is the position location information signal provided by a GPS satellite system. In the GPS system, several satellites transmit a location beacon at about 1575 MHz that may be received by a GPS receiver. The GPS signal contains timing and location information that may be used to determine the location of the GPS receiver. In this way, a mobile wireless device receiving the GPS signal may provide location information for emergency personnel or other applications. The design and construction of a GPS receiver is well known, so will not be discussed in detail.
Even though mobile wireless devices have become more complex, market pressures demand higher performance and lower costs. In this regard, the manufacturing of mobile devices requires trade-offs between features, quality, and price. For example, cost and space may be saved by having one or more communication process share components. In one particular example, the communication radio and the GPS receiver may share a common radio frequency (RF) receive chain. The RF chain may include, for example, amplifiers, oscillators, filters, mixers, and other RF components. Of course, this means that when the GPS receiver is active, the communication radio receiver can not be operated. In another example, it may be desirable to make a less costly phone by using fewer or lower quality components in the GPS receiver. Then, to improve sensitivity to the low power GPS signal, the communication radio is deactivated while GPS data is collected.
Often, then, the communication radio is deactivated for the time period while the GPS data is being collected. This means that any communication call in progress will be suspended so that the GPS receiver may operate. During this suspended time period, which typically extends for several seconds, and even up to as much as one minute in low signal areas, the wireless device will not exhibit normal call activity. For example, the ear speaker may be silent, or the display may appear to be locked. In some circumstances, the user may become concerned with the lack of normal activity and terminate the call, or turn off the wireless device. By doing so, the user may cause errors or delays in the application, or may cause the application to reset and start over. For example, if a mapping application has requested the location for the mobile device, and the user terminates the application while the mobile device is collecting GPS data, then the mapping application will have to re-request the location information. This unduly burdens the communication infrastructure, as well as increases the time for the application to provide useful information.
In a more troubling example, if the user places an emergency call, the user may hear “rings” in the earpiece, and then may hear a “click” as the emergency call center answers the call. Typically, an operator does not answer the call at this point, but the emergency call center sends a request for the location of the mobile device. This request is typically made using signaling or control channels, so the mobile user is unaware that the request has been made. Responsive to the request, the mobile device suspends the communication call, and activates its GPS receiver. Unfortunately, the mobile device no longer exhibits normal call activity, so the mobile user may terminate the call and re-dial 911, or reset the mobile phone because they believe it is not operating correctly. This not only wastes valuable time in contacting emergency personnel, but it also places additional burdens on the emergency communication process and infrastructure.